1. Field of the Invention
This invention relates to a rear discharge mower unit for rearwardly discharging grass clippings cut by blades. The invention relates also to a lawn tractor having such a rear discharge mower unit suspended between front and rear wheels, and a grass catcher disposed rearwardly of the rear wheels.
2. Description of the Related Art
A rear discharge mower unit has a plurality of blades arranged sideways and rotatably supported in a mower housing, and rearwardly discharges grass clippings cut by the blades as entrained by air flows produced by the rotating blades. U.S. Pat. No. 3,469,376, for example, discloses a rear discharge mower unit having four blades arranged symmetrically sideways. The two left blades are rotatable clockwise while the two right blades are rotatable counterclockwise. Thus, all grass clippings are once collected in a middle region, and then thrown rearward through a space between the two middle blades.
U.S. Pat. No. 4,916,887 discloses a rear discharge mower unit having a side blade disposed at each opposite side of a center blade, and a mulching rotary blade disposed between the center blade and right side blade. The left side blade and center blade are both rotatable clockwise, whereby grass clippings cut by these two blades are fed confluently to a region to the left of the mulching rotary blade. Grass clippings cut by the right side blade are fed to a region to the right of the mulching rotary blade. The grass clippings are discharged rearwardly after being cut to pieces by the mulching rotary blade.
The former rear discharge mower unit has only a small space between the mower housing and each blade, and no special path provided for passage of grass clippings. Thus, the grass clippings cut by the blades cannot flow smoothly to the outlet, but tend to stagnate locally before discharge through the outlet. It is difficult to avoid the inconvenience of the grass clippings dropping from stagnating positions.
In the latter rear discharge mower unit, all the blades are rotatable in the same direction, which requires a relatively large distance between the path of grass clippings sent to the outlet by the center blade and the path of grass clippings sent to the outlet by the right side blade. This is obstructive to compactness of the mower housing.